Optical connectors have many applications in fiber optic networks. Their ability to be mated and unmated lend flexibility for transmission routing. Optical connectors can link individual fiber segments together to achieve longer distances. Connectors permit access to terminal transmission equipment. Fiber cable assemblies are terminated with connectors for patching between equipment. Connectors are mounted on fiber test instrumentation for fiber measurement purposes.
Fiber connectors consist of a male ferrule in which a fiber is inserted and mounted. The end face of the fiber protruding from the tip of the ferrule must be polished to create a scratch-free surface. This will maximize light transmission when one connector is mated to another by means of a female coupler.
Light travels through the core of an optical fiber. The core diameter of a standard telecommunication fibers ranges from approximately 9 microns to 100 microns. The size of dust and ambient particulants average between several microns to over 50 microns. If these potential contaminants are present on the polished fiber core, they can obstruct light transmission and create connector loss.
Many modern connectors are polished so that the fiber has a convex curvature and slightly protrudes above the ferrule end face. When two connectors are mated by a female coupler, the two polished fiber surfaces touch and deform each other. This contact is often desired to reduce attenuation and optical back reflection.
The presence of contaminants between contacting fiber core surfaces can be extremely hazardous. These contaminants can easily scratch and pit the polished fiber surfaces. This is especially true during the initial mating when the two ferrules often rotate against each other.
Several methods are currently used to clean fiber surfaces before mating connectors.
Compressed air is sprayed across the ferrule to blow contaminants off the fiber surface. The force is not always sufficient to be effective. This is especially true when using costly self-contained air cans. Additionally, the compressed air propellant can also contaminate the fiber surface.
Lint-free cloths are wiped across the ferrule end face to remove contaminants. These clothes, while manufactured to be "lint-free", can still leave behind material. Additionally, the wiping action can scrape contaminants across the fiber surface.
Often cloths are treated with cleaning agents, such as isopropyl alcohol, to aid in the cleaning process. The effectiveness is highly dependent upon the purity of The agent. Impure agents can leave loss inducing residues on the fiber surface. After application of cleaning agent, compressed air often needs to be applied to evaporate the agent. Local, state and federal codes restrict the use and transport of some of these agents due to their flammability and combustible properties.
Fibers are also wiped against polyester tapes contained in dispensers. As with lint-free cloths, the wiping action can also cause scratches on the fiber surface. Dispensers are often costly to distribute when many users are required.